.3.19 Dust Storm Outbreak Mechanism

The dust storm is a disaster weather phenomenon which often occurs in spring and winter in north of China. A Computational Environmental Modelling System from Dr. Yaping Shao is applied to the sand storm over China in March 2002, and the predictions are in good agreement with meteorological records and satellite images. A dynamical diagnose Based on the data from the model presents us more information than real meteorology record about the outbreak mechanism of the sand storm. It is caused by the frontogenesis of cold front connected with Meng Gu cyclone. Large amount of avaikble potential energy convert to dynamic energy in the baroclinic mesosphere. It result in frontogenesis. As the strong normal share of the wind, turbulent fluctuation is strengthened and the sands are raised up from the surface ground The wind speed in the atmosphere of the low level has a horizontal share and this pushes the sands in the atmosphere aggregate, so the visibility descend. A strong sandstorm is produced. A sensitive experiment is also performed to prove that dynamical instability of low level atmosphere would strengthen the entrainment of the sand particles in surface.